Rearrangements of MLL are regarded as primary oncogenic events in acute leukemia. We report the case of a patient with acute myeloid leukemia with a complex abnormal karyotype at diagnosis who showed a putative stem line with monosomy 5 and a rearrangement of chromosome 17 as the only abnormalities and an evolved clone with an additional t(7,16,11)(p1?4;p13;q23) after treatment. Fluorescence in situ hybridization analysis confirmed that the translocation had resulted in an MLL rearrangement not present in the stem line or in the complex clones found at diagnosis. To date, this is the first report of an MLL rearrangement evolving as a secondary abnormality within a preexisting leukemic clone.
Copyright 2002 Wiley-Liss, Inc.